1. Field of the Invention
This invention relates to a dowel hole drilling machine comprising a workpiece support, stops which are engageable by the workpiece and at least one drilling unit, which is mounted on an angled crosspiece and together with the latter is pivoted on an axis.
2. Description of the Prior Art
In a known dowel hole drilling machine of that kind (Swiss Patent Specification 148,554), the workpiece support consists of an unmovable supporting table, on which the workpiece is movable into engagement with stops. When structural bores for making corner joints are to be drilled, dowel holes must be drilled into the workpiece from its broadside with the drilling unit in a vertical orientation. Dowel holes must be drilled into the other workpiece from its end face with the drilling unit in a horizontal orientation. The accuracy of said drilling operations depends on the exact coordination of the pivotal axis with the workpiece support and the stops. For instance, if the pivotal axis of the crosspiece carrying the drilling unit is not exactly at right angles to the direction in which the workpiece is advanced, the bores will have a smaller distance from the reference edge on one side of the workpiece than on the opposite side. That fault will have serious consequences because the associated workpiece is drilled with the same drilling unit but in a different plane when said unit has been pivotally moved so that the dowels fitted into the bores in one workpiece will not fit the bores in the associated workpiece when the associated edges of the two workpieces are required to exactly contact each other.